1. Field of the Invention
The invention relates to a droplet ejecting device and, more particularly, to the structure of an ejection port.
2. Description of Related Art
A bubble jet type ink jet printer using an electrothermal converting element as a pressure generator and a piezoelectric type ink jet printer using an electromechanical converting element as a pressure generator have been recently noticed for the reason of low noise in comparison with an impact type printer. For example, in the piezoelectric ink jet printer, the capacity of an ink passage is changed according to dimensional displacement of a piezoelectric actuator. Ink held in the ink passage is ejected through an ejection port when the capacity is decreased, while ink is introduced into the ink passage when the capacity is increased. This is called a drop-on-demand system. A multiplicity of ejectors operating as described above are arranged close to each other. Ink is ejected from the ejector located in a predetermined position whereby a desired character or image is formed.
In an array 1 constituting a conventional droplet ejecting device, the assembly perspective view being shown in FIG. 6, a cover 6 is joined to a grooved plate 2 having numerous ink passages 4 formed of grooves defined by side walls 7. A nozzle plate 8 having ejection ports 10 corresponding one to one to the ink passages 4 is bonded to the end surface of the assembly constituted of the grooved plate 2 and the cover 6. Accordingly, it is necessary to form the same number of ejection ports 10 as that of ink passages 4 thereby inducing the problem of many manufacturing processes. In addition, in order to eject ink at low energy, each of the ejection ports 10 ought to be formed into a tapered shape contributive to a decrease in ink passing resistance, with attendant problems of complicated manufacture and high manufacturing costs.